At wits end with charging system

[Twister]

So ever since I bought my first Bronco II 4 years ago I have hard the worst, and I mean worst luck with the charging systems. I would go through car batteries about twice a year. Luckily by Walmart battery had a non bs replacement warranty. So I just did the 3g alt swap on my 87 B2 about 1.5 months ago, everything was working great, not one problem. I was getting 14.5v and up are idle with all the accessories on. Well, I went to start it last night, and it was dead :banghead:. I haven't gotten to test it or anything, but any tips before I mess with it? What is the best way to charge the battery before I start it so I don't harm it?

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[RonD]

14.5vDC at the battery when engine is idling to too high, you are damaging the battery.

At idle you should see 13.8vDC, maybe as low as 13.5vDC if all electrics are on, lights, fans, etc....
14.2vDC is ok at higher RPM, but 14.5vDC would start to damage battery.

I would have the voltage regulator checked, or look at the specs on that alternator.
A 60amp or a 90amp alternator should output the same voltage, 13.8-14.2vDC, a 90amp can just maintain the lower 13.8vDC longer as more electrics are added to the system, i.e. driving lights, sound system amplifiers and wenches.
So you don't get the dimming lights at idle.


If you test a battery with engine off it should show 12.6vDC or higher, and it should be steady not dropping because meter is connected.
A battery has 6 cells inside, each should have 2.2vDC when new for a total of 13.2vDC but usually they run 12.8vDC -13vDC when new.

When battery gets down to 12.4vDC, after being charged, it is time to get another one as it can no longer hold a full charge, if you see small voltage drop while meter is connected then one of the cells has a short in it and battery will drain itself over a few hours, overnight and then "click, click" no start.
The most common cause of battery failure is a shorted cell, this can be made to happen quicker by over voltage charging, the 14.5vDC and higher.

 

[Twister]

14.5vDC at the battery when engine is idling to too high, you are damaging the battery.

At idle you should see 13.8vDC, maybe as low as 13.5vDC if all electrics are on, lights, fans, etc....
14.2vDC is ok at higher RPM, but 14.5vDC would start to damage battery.

I would have the voltage regulator checked, or look at the specs on that alternator.
A 60amp or a 90amp alternator should output the same voltage, 13.8-14.2vDC, a 90amp can just maintain the lower 13.8vDC longer as more electrics are added to the system, i.e. driving lights, sound system amplifiers and wenches.
So you don't get the dimming lights at idle.


If you test a battery with engine off it should show 12.6vDC or higher, and it should be steady not dropping because meter is connected.
A battery has 6 cells inside, each should have 2.2vDC when new for a total of 13.2vDC but usually they run 12.8vDC -13vDC when new.

When battery gets down to 12.4vDC, after being charged, it is time to get another one as it can no longer hold a full charge, if you see small voltage drop while meter is connected then one of the cells has a short in it and battery will drain itself over a few hours, overnight and then "click, click" no start.
The most common cause of battery failure is a shorted cell, this can be made to happen quicker by over voltage charging, the 14.5vDC and higher.

Thanks. The charging system on these trucks is far to sensitive. I know no one that has the problems I have with it. If the battery is dead then the truck will be sitting for awhile

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[4x4junkie]

14.5VDC is 100% normal during warm-up (on a very cold morning, even 15+ VDC will be present for a few minutes), however it should drop down to around 14.2 and maintain that once it's reached full operating temp.

Purpose for this is to get a better charge back into a cold battery after starting.


Lots of good info on this site:
www.batteryfaq.org



To the OP,
Disconnect the battery and try putting a charger on it for about an hour.
If you have one of those new whizz-bang electronical chargers that error out because a battery is too low, try an old-tech manual "dumb-charger" on it for about 10 minutes first (it might kick on & off a couple times at first, but should get going after a bit), afterward the electronic one should then work.

If this was a sudden occurrence (and you didn't leave something turned on), I'd be suspicious of a shorted rectifier in your alternator (I had this happen on mine once, drained both my big #27 deepcycle batts dead-dead overnight).
This led to a 3G upgrade for me as well.

 

[Twister]

14.5VDC is 100% normal during warm-up (on a very cold morning, even 15+ VDC will be present for a few minutes), however it should drop down to around 14.2 and maintain that once it's reached full operating temp.

Purpose for this is to get a better charge back into a cold battery after starting.


Lots of good info on this site:
www.batteryfaq.org



To the OP,
Disconnect the battery and try putting a charger on it for about an hour.
If you have one of those new whizz-bang electronical chargers that error out because a battery is too low, try an old-tech manual "dumb-charger" on it for about 10 minutes first (it might kick on & off a couple times at first, but should get going after a bit), afterward the electronic one should then work.

If this was a sudden occurrence (and you didn't leave something turned on), I'd be suspicious of a shorted rectifier in your alternator (I had this happen on mine once, drained both my big #27 deepcycle batts dead-dead overnight).
This led to a 3G upgrade for me as well.

It was a sudden occurrence, i was great till yesterday. When i first started it up when i was running it would spike at around 15 -14.9v and would drop as the truck warmed up, i dont think i ever checked it when it was fully warmed up. I have it on a charger now on its lowest settings and i am going to let it sit for an hour or two and see if it come back. How would i know if the rectified is bad or the regulator? Is there anyway to test either one. Sorry i a sound lame, i know nothing of the charging system lol

 

[RonD]

I know if you read it on the internet it must be true...........................lol.
www.batteryfaq.org


But, over 14.4vDC at the battery when idling will ruin a car battery over time.
High idle at 1,100rpm might be 14.2vDC, when you get up into the 14.7vDC range you will have problems.
700rpm idle should be around 13.8vDC down to 13.5vDC with a load.

 

[Twister]

Well I charged yesterday for about 1.5 hrs, it started so I took a nice 45 min drive. It started up great today, so ill get some volt readings when my brother gets home as I don't have a multi meter.

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[4x4junkie]

You'll know a shorted rectifier when you go to reconnect the battery, there'll be a real heavy current draw (spark) each time you touch the cable to the terminal (normal is a light spark initially, followed by no further spark unless you wait a number of seconds to connect it again)

I know if you read it on the internet it must be true...........................lol.
www.batteryfaq.org


But, over 14.4vDC at the battery when idling will ruin a car battery over time.
High idle at 1,100rpm might be 14.2vDC, when you get up into the 14.7vDC range you will have problems.
700rpm idle should be around 13.8vDC down to 13.5vDC with a load.

Well, I guess with it taking fully 9-10 years for the above voltage algorithm to "ruin" my batteries, I guess I can't really complain.

 

[Tedybear]

Actually 14.5 volts DC is the upper end of NORMAL for a charging system. And yes, that was also in the several automotive text books when I was in college for automotive tech. Not saying that 14.5 is the end all and be all of charging, as the regulator will turn that voltage up/down according to load/demand and of course--engine RPM (the faster it spins? The higher supply available).

If the alternator you feel is putting out a bit to much? A local shop suggested running another ground strap/wire coming off the alternator housing and going directly to battery ground terminal. He made that suggestion after figuring out that some teenager (most likely....this thing is pot marked with speaker mount holes and sub holes...and amp holes...) Someone modified the alternator to accept a much higher output one that came out of a much larger Ford Truck. I had to remove the alternator and take it to the shop for them to compare, as nothing in any of the parts catalogs matched up.

The tech's advice? (and this is from a tech that has been rebuilding these things for 30+ years....) If it's overcharging? Run another ground wire from the alternator to the battery neg. Will it work? Not sure? The alternator at my end runs at the higher end of normal (14.6 nominal) and it's been over a year without issues.

S-

 

[Twister]

Well its output seems to vary day to day. I tested it now with it up to temp. Idling at around 850-900, with just the head light on and in park it read 14.9v. I turned everything I could minus the stereo (lights, front and rear wiper, turn signal, rear defrost) it dropped down to 14.5v. This was with the outside temp at 25*F

Also I used a very large positive cable and have already added another ground from the alt case to the negative battery terminal
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[iTurbo]

Does sound too high. Does anybody know if there is temp sensor in the voltage regulator circuit that lets it charge a little higher if it is cold out? This is common on several manufacturers. Perhaps the 'battery temp sensor' or 'charging temp sensor' is on the way out..

 

[RonD]

It sure reads like your voltage regulator isn't working, i.e. voltage to rotor isn't changing.
With no electrics on, voltage should be stable, as you turn on lights the voltage might drop and then come back up, thats the regulator working.
Yours only seems to drop???

Are all 3 wires coming out of the regulator hooked up
A - (yellow)goes to either B+ on alternator or to Solenoid (Battery side)
S - (gray or white)is a short jumper to single plug on alternator(this wire can get frayed ends, only 1 or 2 strands holding it)
I - (green) goes to Key switch via voltage meter or "charge light" in dash board
(does your dash meter or "light" work, if not that could be the problem)

Also check your digital multimeter, with engine off battery voltage should be 12.6-12.8vDC
If it's showing higher then meter is off.

Cold effects the batteries ability to convert the chemical reaction into amperage when starting, chemical reaction is just slower when colder.
And for the same reason recharging a battery can take a bit longer, when temps are low.


The voltage regulator controls the alternators output by reducing or raising the voltage going to the rotor, that is what the brushes are for, to control the output voltage.
The rotor is an electro-magnet, it spins inside 3 "fields", the 3 fields supply the power to the charging system(B+), spinning magnet = electric power, stronger magnet = more power, so as voltage at the brushes is increased the magnet becomes stronger.
The regulator might supply the rotor 6volts for a basic load, as more electrics in the vehicle are turned on the regulator will increase the rotors voltage to 10volts, stronger magnetic power in the rotor increase the output of the "fields".

So if every thing is working as it should, you should see a stable voltage until you reach the amp limit of the alternator.
So engine warmed up, idle at 700rpm, battery recharged after starting, ALL electrics OFF.
Measure voltage at battery, should be about 14v, 13.8-14.2, now turn on the electrics, you might see a drop then back to 14v.
With everything on you might see a .2 drop, more than that and you are at the amp limit of the alternator.
A charging system can maintain the batteries charge down to about 13.5vDC below that and battery won't be charging and below 13.2vDC battery will be discharging.

From your description all you see is a drop in voltage as things are turned on, so rotor voltage is fixed, the regulator isn't changing it, so it is stuck on 12v, full output.


The chemicals in a battery start to turn to vapor at about 2volts above battery voltage, so if a battery shows 12.6vDC at rest then a charge voltage of 14.6vDC will start the vapor process, the new sealed batteries are better at resisting this, they condense vapor to return to battery.
But prolonged +2volts can take its toll.


And I believe the Ford 3G is a Type A regulator, it uses the rotors Ground brush to control the voltage going to the rotor.
Type B uses the + voltage brush.
Type I uses both brushes, I think chrysler used this.

So with a Ford 3G running a Ground wire from alternator case would be a good idea, just to make sure everything is connected.

 

[4x4junkie]

I would agree, 14.9 fully warmed up is a bit high. I would expect ~14.5 or so with the outside temp you mention, as the air coming through the radiator hitting the alt would still be much cooler than on a warm day (the temp sensor is built into the voltage reg module on back of the alt).

Also agreed on checking your meter's accuracy. It seems your alt is charging and regulating, maybe if not at the right voltage... (usually when a VR goes out, they quit working altogether).

Battery voltage should be ~12.65V after sitting overnight if it's a standard low-maintenance type battery, 12.75-12.78 if it's a sealed maintenance-free or AGM battery.
Charge it fully to 100%, then let it sit disconnected overnight (inside, preferably) and see if your meter reads it's voltage as above. If it doesn't, then you know your meter is faulty. But if it does, then I'd try replacing the voltage regulator on your alt, as the alt itself (windings & rectifier) seems to be in working order.

 

[Twister]

I think my alt killed my battery again . With my truck just sitting off, the voltage on the battery just drops

 

[RonD]

Yes, one of the cells in the battery has a short in it, so it is draining the others.
That's the normal end-of-life for most batteries, but usually doesn't happen for 5 to 7 years of discharge/recharge.

At least it's still under warranty

I would certainly get the voltage regulator working ASAP